Hydraulic cylinder



United States Patent Patrick P. Lee Tonawanda, New York 816,691 .m 9,12 2 V Continuation-impart of Ser. No. 735,666, e 0, Sept. 15,1970 p iiyTne'ha'ssi'giini'eht's, t6

Integrated Dynamics Incorporated, mater a," Connecticut a corporation of Connecticut.

inventor Appl. No. Filed Patented Assignee HYDRAULIC CYLINDER 9 Claims, 4 Drawing Figs.

U.S. Cl 92/128, 92/ l 65 Int. Cl. F0lb 29/08 Field of Search 92/128,

Primary Examiner-Martin P. Schwadron Assistant Examiner-Leslie .1. Payne Attorney-Christel and Bean ABSTRACT: The piston of an hydraulic actuator is removable from its cylinder by withdrawing a pin through the fluid inlet for the cylinder. The pin engages behind a stop collar received on the inner end of the piston. The collar engages a stop shoulder on the cylinder, and is slidable from the piston upon removing the pin which fits loosely in an opening through the piston.

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Patented Sept. 15, 1970 v INVENTOR. PA TRICK R 45.5

BY Ma /3w A TTOPNEYS HYDRAULIC CYLINDER CROSS REFERENCE TO A RELATED APPLICATION This application is a continuation-in-part of my pending application Ser. No. 735,666, filed June 10, 1968, entitled Hydraulic Cylinder.

BACKGROUND OF THE INVENTION Hydraulic actuators of the type contemplated herein are characterized by a cylinder construction that includes a chamber-forming portion closed at one end and having a bearing portion at the other end which snugly but slidably receives a piston, there being a suitable hydraulic fluid inlet leading into the chamber for receiving pressurized hydraulic fluid to force the piston to be displaced axially outwardly with respect to the cylinder. An abutment or stop on the inner end of the piston limits the working stroke of the piston and prevents the piston from being forced completely out of the cylinder.

In actuators of this type, it is of concern to provide fabrication procedures which minimize production cost and, to this end, the cylinder is constructed to be integral or of permanently joined parts so that it may not later be disassembled.

It is also desirable, however, that the piston be removable so that it may be replaced during service when required and this has led to the development of means for internally separating the piston and its stop or abutment member by manipulation through the hydraulic fluid inlet. Examples of such constructions may be found in the Miller U.S. Pat. No. 2,724,368 of Nov. 22, 1955 and in the Zimmerer U.S. Pat. No. 2,997,026 of Aug. 22, I961.

BRIEF SUMMARY OF THE INVENTION The construction according to this invention involves the use of an abutment collar or ring more or less loosely fitted on the inner end of the piston, in combination with a retaining pin disposed behind the collar and which may be registered with the hydraulic fluid inlet for removal therethrough to allow the collar to be separated from the piston and the piston to be withdrawn from the cylinder. The parts may be reassembled by reversing the procedure.

The main advantage of this assembly is that the collar presents a flat face, normal to the axis of the piston, which is sufficiently large as to distribute the bearing load at full extension of the piston over a large area, with the result that the shoulder of the cylinder against which the collar engages is not likely to become distorted, damaged or destroyed. Moreover, the cylinder shoulder is very easily and inexpensively formed, particularly where such shoulder is formed as the end face of a bearing portion received within and welded to a central body portion of the cylinder.

Further in accordance with this invention, the retaining pin is flat-sided, presenting to the collar a load distributing bearing surface of substantial area thereby reducing stress and strain on the collar to avoid distortion thereof and maintain the integrity of the assembly.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial section of the cylinder showing the piston and its abutment assembly associated therewith;

FIG. 2 is a view showing one end of the assembly in FIG. 1 illustrating the manner of separating the parts;

FIG. 3 is a transverse section taken along the plane of section line 3-3 of FIG. 1; and

FIG. 4 is a fragmentary plan view taken about on line 4-4 of FIG. 1 and showing the assembled pin and collar.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, the cylinder includes the central or main body portion 12 which may be a piece of tubular stock cut to the required length and permanently joined by weldments l4 and 16 to the end closing portion 18 and the bearing portion 20. The bearing portion 20 presents a smooth inner surface 22 line is connected to the assembly. As is also clear from FIG.

1, the wall of the main body portion 12 may be bored to provide the inlet opening 32, and counterbored to receive the end of the nipple 30, after which the parts are welded as at 34.

The bearing portion 20 is simply cut off or faced at its inner end to provide an annular stop shoulder 36 and this inner end portion of the bearing portion 20 is received within the end of the main body portion 12 to serve as a locating pilot between these parts prior to their permanent attachment. In the embodiment shown, the inner end of the bearing portion is of reduced diameter positively to locate the parts 12 and 20 axially.

The major extent of the piston is of uniform diameter for sliding within the bearing portion 20, and the piston is hard faced or chromed for maximum wear characteristic. The inner end 38 of the piston 24 is of reduced diameter to receive the stop collar 40 which presents a flat, annular face 42 adapted to engage the stop shoulder 36 and limit the working stroke of the piston and normally prevent withdrawal of the piston from the cylinder. The collar 40 is, in turn, held in assembled relation with respect to the piston by means of the pin 44 removably received in the transverse bore 46 in the piston and seating behind the collar 40, as shown. Collar 40 can be a simple washer, providing a continuous annular stop face.

The pin 44 is of smaller diameter than the inlet opening 32 and fits loosely in bore 46 so that, with the cylinder turned as in FIG. 2, the pin 44 may be brought into registry with the inlet opening whereupon it can drop through the opening and allow the collar 40 to separate from the piston 24. Forcing is not required nor is it necessary to insert a tool through opening 32 in order to effect such separation. The piston may then be withdrawn from the cylinder and repaired or replaced if necessary. To aid in re-engaging the collar 40 on the inner end 38 of the piston, the end of the piston may be chamfered as indicated at 48, and the pin 44 is simply reinserted through the opening 32 behind the collar to effect reassembly of the parts. After the parts are assembled, piston 24 is rotated relative to cylinder 10 to position pin 44 out of registry with inlet 32.

The relatively large contact area between the collar 40 and the shoulder 36 minimizes the bearing pressure therebetween and prevents any localized pounding which might distort the inner end of the bearing portion 20. In this way, the shoulder 36 may be simply a flat face without regard for forming a relief area around its inner edge to prevent binding on the piston due to localized damage of the bearing portion inner end face. Thus, no special machining is required in this area.

While pin 44 could be a simple, cylindrical pin, it would then provide only line contact with collar 40. Upon extension of piston 24 and engagement of collar 40 against stop shoulder 36 to limit the working stroke of the piston, collar 40 engages pin 44 and is stressed thereby. The strain on collar 40 would be highly localized by line engagement with pin 44, and might result in distortion of collar 40, reducing the contact area between collar 40 and shoulder 36 and thereby disrupting the integrity of the assembly.

Therefore, it is a further feature of my invention that pin 44 is flat-sided, to provide a collar-engaging, load-distributing bearing surface 50 of substantial area.

The flat side 50 defines a chordal plane across the basically cylindrical shape of pin 44, and extends from one end of the pin to the other. In providing surface 50, material can be removed from originally cylindrical stock, only a minor portion of the radius thereof being removed to form a flat bearing surface of substantial area without materially reducing the strength of the resulting pin. In the illustrated embodiment, the opposite ends of pin 44 are themselves flat and chamfered at, for example, a 45 angle. Surface 50 is formed by removing material to the width of the chamfer, as clearly shown in H6. 4. Alternately, initially flat-sided stock can be used.

In this way, the bearing load on collar 40 upon engagement thereof with pin 44 is distributed by surface 50 over a substantial area, thereby relieving the strain on collar 40. Pin 44 remains free floating in bore 46, except that it is free to rotate only through a relatively small angle, this being limited by engagement of the opposite side edges of surface 50 with collar 40, thereby maintaining the angular orientation of pin 44 relative to collar 40 with surface 50 facing collar 40 for engagement therewith.

.Thus, there is provided a simple yet effective construction. Collar 40 is inserted into cylinder through one end prior to permanent attachment of its parts at that end, and is readily assembled on and removed from the piston end. Once the cylinder parts are permanently assembled, collar 40 remains therein, being so dimensioned and arranged that it cannot inadvertently fall out of the cylinder upon removal of the piston. The length of pin 44 is less than the inner diameter of cylinder portion 12, being approximately equal to the outer diameter of collar 42. Pin 44 is free to float in bore 46, into engagement with the wall 26 of cylinder portion 12 which retains pin 44 in the piston bore with its opposite ends engaging behind collar 42.

I claim:

1. An hydraulic actuator piston and cylinder assembly of the type having a cylinder formed with a central portion closed at one end and having a bearing portion at its other end, a piston axially slidable in said bearing portion and having an inner end portion, an annular abutment shoulder adjacent the juncture of said central and bearing portions, stop means carried by said piston, and an opening extending laterally from said central portion, the improvement comprising:

said stop means being in the form of a removable collar surrounding said inner end portion of said piston for engaging said abutment shoulder to distribute bearing loads over substantially the entire surface of said abutment shoulder;

said piston having a transverse bore at its inner end; and

and a pin received in said transverse bore behind said collar normally to prevent removal of said piston from said cylinder, said pin being of a diameter to permit removal thereof through said opening.

2. An hydraulic actuator assembly as defined in claim 1 wherein said bearing portion includes an inner end received in said central portion, said inner end having a square face forming said abutment shoulder.

3. An hydraulic actuator assembly as set forth in claim 1, wherein said opening comprises an inlet for hydraulic fluid.

4. An hydraulic actuator assembly as set forth in claim 1, wherein said pin is loosely received in said transverse bore and floats therein, said central portion having a wall and said pin normally being constrained against removal from said bore by said wall of said central portion.

5. An hydraulic actuator assembly as set forth in claim 4, wherein said collar provides a continuous flat, annular face for engagement with said abutment shoulder, said pin being flatsided to provide a flat bearing surface for engagement with said collar, said pin, collar and bore being dimensioned and arranged to permit said pin to float in said bore while constraining said pin against rotation of said bearing surface away. from said collar.

6. An hydraulic actuator assembly as set forth in claim 1, wherein said inner end portion of said piston is of reduced diameter relative to the major portion of said piston, thereby defining a shoulder between said piston portions, said collar being confined between said piston shoulder and said pin.

7. An hydraulic actuator assembly as set forth in claim 6, wherein said collar is slidable axially from said inner end of said piston upon removal of said pin from said bore.

8. An hydraulic actuator assembly as set forth in claim 1, wherein said collar provides a continuous, flat, annular face for erigaglement with said abutment shoulder. I

9. n ydraulic actuator assembly as set forth in claim 1, 

